Generally, in order to provide superior medication delivery devices which are likely to be well received by particular groups of patients, a greater diversity in drug delivery systems have been launched to the benefit of patients. As the number of commercially available delivery systems increase, numerous different types of medication holding cartridges or containers are distributed. Most of these types of containers differ in various aspects.
Each medicament container may be filled with a particular type of medicament selected from a large variety of different medicaments, but also different kinds of the same class of medicament (e.g. rapid or long acting insulin) and different concentrations of each particular medicament may be accommodated in the containers.
Moreover, different container volumes may be introduced in order to customize each container, and, thus, the delivery system to the needs of particular users. Variation of container volume may be provided by changing the length or diameter of the container. These modifications usually imply corresponding modifications of the dosing assembly of a medication delivery system, so as to provide a particular stroke of a driving element for expelling the medicament from the container or to provide optimal dosing precision. Further discrimination between different medicament containers may be occasioned by the design requirements for each particular delivery system, such as required sliding friction of the piston accommodated in the container.
In order to discriminate between a larger variety of available containers, numerous container coding and coupling systems have been developed. The following mechanical coding and coupling systems are known in the art:
U.S. Pat. No. 5,611,783 relates to a pen shaped syringe comprising a distal part which may comprise an ampoule and a proximal part containing a dose setting and drive mechanism. The proximal and distal parts have interlocking bayonet coupling means. Protrusions may be provided to form a pattern ensuring that a certain distal part may only be used in connection with a certain proximal part.
WO 03/017915 A1 discloses a cartridge having a distal end provided with a mechanical coding. The mechanical coding has the form of a circular protrusion where the circular outer diameter is dedicated a specific concentration of insulin contained in the cartridge.
U.S. Pat. No. 5,693,027 discloses a plastic top for adapting a standard cartridge to a chosen syringe. The plastic top may be provided with means for keyed engagement with corresponding means in a syringe to keep it unrotable when mounted with a cartridge in the syringe. In some types of syringes such keyed engagement between cartridge and syringe is further used to ensure that only a certain type of cartridge is used.
U.S. Pat. No. 6,648,859 B2 discloses a drug cartridge assembly for use with a reusable pen body assembly of a medication delivery pen. In order to eliminate cross-use the pen body assembly and the drug cartridge are keyed i.e. they may be threadedly engaged by corresponding threads and grooves, bayonet threads, and grooves, snap fits or a pair of lugs that mate in reverse Luer-Lock manner. The mating members are selected so as to prevent cross-use with other assemblies, e.g., the pitch of the threads may be angled so as to mate only with one another and not with other assemblies.
Yet another prior art system is described in DE 201 10 690.
GB patent No. 301,961 discloses a syringe wherein a barrel member holding an ampule is provided with a radially extending pin which is cooperating with a bayonet slot formed in a head. The head is attached to the barrel by a conventional bayonet coupling movement including a relative rotational movement between barrel and head.
It is an object of a preferred embodiment of the present invention to provide an alternative to the known systems. Furthermore, it is an object of a preferred embodiment of the present invention to provide a medication delivery system with a large number of possible coding geometries, while obtaining a robust coding system.
Furthermore, it is an object of a preferred embodiment of the present invention to provide a coding system wherein the user experiences substantially the same operational fastening/coupling/locking movement when the container and dosing assembly of a predetermined medical delivery system are coupled/uncoupled (locked/unlocked) to each other regardless of the specific choice among sets of compatible container/dosing assemblies.
Furthermore, it is an object of a preferred embodiment of the present invention to provide an intuitive and simple fastening mechanism for fastening the container to the dosing assembly.
Moreover, it is an object of the present invention to provide a locking/fastening system wherein the user experiences an auditive or tactile feed back when locking the container to the dosing assembly.